The technology included and excluded have all been design decisions. It could easily be argued that technologies omitted are just as important or more so that those included.
Some technologies such as machine guns are assumed to have been developed by both sides and represented by combat bonuses for the defender once trench warfare begins. U-boat improvements are reflected in the naval operations phase of the game without a dedicated technology track.
Current playtesting has seen some extreme strategies and/or the ignoring of certain technologies altogether. For example, with such a limited economy Allied players have forgone gas technology and simply waited to develop the counter technology, the gas mask. Other circumstances may have contributed to that such as early air losses.
As playtesting continues, technology is one aspect of the game we’re keeping a close eye on.